mechanical assembly for securing the structural integrity of a pipe joint

ABSTRACT

A mechanical securing assembly ( 40 ) is adapted to secure the structural integrity of a flow passage formed by at least a first pipe part ( 41 ) and a second pipe part ( 42 ). The assembly comprises a connecting member ( 43 ), a first fastening member ( 44 ), attached to the connecting member and adapted to secure the connecting member to the first pipe part, and a second fastening member ( 45 ), attached to the connecting member and adapted to secure the connecting member to the second pipe part. The connecting member comprises a spring element ( 46 ) exerting a force pulling the first fastening member and the second fastening member towards each other along a primary axis (y), and thus being adapted to force the first pipe part and the second pipe part towards each other. The spring element is extendable along the primary axis by a compression of the spring element along a secondary axis forming an angle to the primary axis.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to the field of repairingcracked pipes in nuclear plants. More specifically, the presentinvention refers to a mechanical securing assembly for securing thestructural integrity of a pipe joint of two or more pipes or a pipeforming a fluid passage in a nuclear plant. Especially, the presentinvention refers to a mechanical securing assembly adapted to secure thestructural integrity of a flow passage formed by at least a first pipepart and a second pipe part, the assembly comprising a connectingmember; a first fastening member attached to the connecting member andadapted to secure the connecting member to the first pipe part; and asecond fastening member attached to the connecting member and adapted tosecure the connecting member to the second pipe part, wherein theconnecting member comprises a spring element exerting a force pullingthe first fastening member and the second fastening member towards eachother along a primary axis, and thus being adapted to force the firstpipe part and the second pipe part towards each other.

BACKGROUND OF THE INVENTION AND PRIOR ART

A nuclear reactor in a nuclear plant has a reactor pressure vessel, RPV,which typically has a generally cylindrical shape and is closed in bothends, e.g., by a bottom head and a removable top head, to form a closedcontainer. A core plate and a top guide are arranged inside the reactorpressure vessel with the top guide arranged on top of the core plate.The top guide comprises a number of holes. A reactor core in the form offuel bundles is arranged inside the reactor pressure vessel with eachfuel bundle being arranged through a hole in the top guide and restingon the core plate. Some reactors are provided with a core shroud whichsurrounds the core, the core plate and the top guide.

The reactor pressure vessel is filled with water covering the core andthe shroud. The water in the reactor pressure vessel is arranged to flowthrough the core in order to cool the core during operation of thenuclear reactor. The flow is usually induced by circulation pumpsarranged between the shroud and the nuclear reactor pressure vesselwhich makes the water flow downwards in the space between the shroud andthe reactor pressure vessel wall. The circulation pumps may be of any ofa number of different types.

In case of a so-called loss-of-coolant accident, LOCA, a rupturing ofthe recirculation duct system or the steam duct system during operationcan cause coolant water to flow out of the reactor pressure vessel,thereby lowering the water level in the reactor pressure vessel andexposing the core in such a way that the fuel assemblies may beoverheated and damaged. In order to prevent such overheating, thenuclear reactor comprises a core spray system including core spraysupply piping, which is supplied via an inlet T-box assembly andconnected to an upper tubular core spray sparger and a lower tubularcore spray sparger above the core via a respective T-box assembly. Thejoints between the T-box assembly and the core spray spargers may besubjected to stress corrosion after long term use as acknowledged inU.S. Pat. No. 5,964,029. Such stress corrosion can result in crackswhich can lead to leakage. Various methods and devices have beenproposed for repairing such cracks.

U.S. Pat. No. 5,964,029 discloses a mechanical securing device adaptedto secure and maintain a tubular cracked piping in a boiling waterreactor. The known device comprises a first clamp operative to securethe device to a piping on one side of a crack, and a second clampoperative to secure the device to the piping on the opposite side of thecrack. A bolt is connected between the clamps to exert an axial forcetending to close the crack. A spring element disposed between the boltand at least one of the clamps for maintaining a tensile force duringthermal transients when the piping tends to contract due to theintroduction of cold core spray water.

US 2006/0082139 discloses a core spray sparger T-box clamp apparatusadapted to be mounted to the T-box for a lower internal sparger inside ashroud of a reactor vessel.

U.S. Pat. No. 6,375,130 discloses an apparatus for clamping a core spraydistribution header, comprising a first clamp on a first distributionheader pipe, a second clamp on a second distribution header pipe and aconnection body block connecting the first and second clamps. Each clamphas an upper clamp body and a lower clamp body. Also the connection bodyblock has an upper body and a lower body.

For instance the T-box assemblies at the core spray spargers areprovided at a location in the reactor pressure vessel, which isdifficult to reach for maintenance, repair or replacement. Since therepair has to be performed under a short period of time, there is a needfor an assembly which may be mounted in an easy and quick manner.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an assembly forrepairing and securing piping in a nuclear reactor. A further object isto provide such an assembly that is easy to mount and attach to defectpipes. A still further object is to provide such an assembly, whichsecure the structural integrity of the fluid passage in an reliablemanner. A still further object is to provide such an assembly which isadapted to compensate for dimensional changes at the clamping areascaused by temperature variations.

These and further objects are achieved by the mechanical securingassembly initially defined which is characterized in that the springelement is extendable along the primary axis by a compression of thespring element along a secondary axis forming an angle to the primaryaxis.

By means of such a spring element the mounting of the assembly isfacilitated. By compressing the spring element, by any suitable tool,the connecting member is prolonged so that it may more easily beattached to the pipe parts at any locations which possibly have beenprepared in advance to receive the first and second fastening members.When the attachment of the first and second fastening member iscomplete, the compressing force is released, whereby the spring elementwill exert a force pulling the first fastening member and the secondfastening member towards each other along a primary axis, and thus alsothe first pipe part and the second pipe part towards each other. Such aspring element will provide a sufficient force also if the pipes to besecured are subjected to length changes due to temperature variations.Consequently, the structural integrity of the fluid passage, which is atleast partly formed by the pipe parts may be secured in a convenientmanner. It is to be noted that the assembly is suitable for securing thetwo pipe parts directly against each other to provide a structurallyintegrated pipe at any location in the nuclear plant or nuclear reactor.The assembly is also suitable for securing the two pipe parts towardseach other in case there is an intermediate component between the pipeparts, which constitutes a further part of the fluid passage. Such anintermediate component may, for instance, be any one of the T-boxassemblies included in the nuclear plant.

According to an embodiment of the invention, the spring element has anannular shape. Such an annular shape may be circular or substantiallycircular, oval, elliptic or the like. Also a polygonal basic shape ispossible, although the corners of such polygon advantageously arerounded.

According to a further embodiment of the invention, the connectingmember has a first portion, extending between the first fastening memberand the spring element, and a second portion extending between thesecond fastening member and the spring element. Advantageously, thefirst portion and the second portion may extend in opposite directionsfrom the spring element, e.g. in parallel with the primary axis.

According to a further embodiment of the invention, the spring elementis made of sheet metal. All parts of the connecting member, i.e. thespring element, the first portion and the second portion, may thus forman integrated part made of one single piece of sheet material. Theconnecting member may have a flat or plane shape.

According to a further embodiment of the invention, each of the firstfastening member and the second fastening member comprises a primarybolt member adapted to be secured in a primary recess in the first pipepart and the second pipe part, respectively. Such a bolt member may inan easy manner be attached to the pipe part only by being insertedthrough a straight movement. The recess may advantageously have abottom, but may also according to an alternative embodiment extendthrough the wall of the pipe part.

According to a further embodiment of the invention, the assemblycomprises means adapted to secure the connecting member to the pipeparts with respect to a direction being perpendicular to the primaryaxis. In case the fastening member is attached merely by one primarybolt inserted into the recess, the connecting member is advantageouslyalso secured in the direction perpendicular to the primary axis by suchmeans in order to reduce the risk that the connecting member is releasedfrom the pipe parts. To that end such means may comprise, in each of thefirst fastening member and the second fastening member, a secondary boltmember adapted to be secured in a secondary recess in the first pipepart and the second pipe part, respectively. Each of the primary boltmembers may extend along a primary direction into the primary recess andeach of the secondary bolt members along a secondary direction into thesecondary recess, wherein the primary direction then may form an anglewith the secondary direction. In such a manner, the connecting member issecured at the pipe parts.

According to an alternative embodiment of the invention, each of theprimary bolt members extends along a primary direction into the primaryrecess and each of the secondary bolt members extends along a secondarydirection into the secondary recess, wherein the primary direction issubstantially opposite to the secondary direction.

According to a further embodiment of the invention, said means comprisesa clamping member adapted to secure the connecting member to the pipeparts with respect to a direction being perpendicular to the primaryaxis by enclosing at least a part of an outer periphery of at least oneof the first pipe part and the second pipe part. With such a clampingmember only one primary bolt member for each pipe part is needed. Such aclamping member may be specifically adapted to extend partly around oneof the pipe parts connected to an intermediate T-box assembly. Theclamping member may then comprise a first plate provided outside thespring element and comprising a first clamp element, and a second plateprovided outside the first plate and comprising a second clamp element,wherein the plates are rotatable relatively to each other to displacethe clamp elements towards and away from each other.

According to a further embodiment of the invention, the assemblycomprises a further connecting member; a further first fastening memberattached to the further connecting member and adapted to secure thefurther connecting member to the first pipe part; and a further secondfastening member attached to the further connecting member and adaptedto secure the further connecting member to the second pipe part, whereinthe further connecting member comprises a spring element exerting aforce pulling the further first fastening member and the further secondfastening member towards each other along a primary axis, and thus beingadapted to force the first pipe part and the second pipe part towardseach other, and wherein the spring element is extendable along theprimary axis by a compression of the spring element along a secondaryaxis forming an angle to the primary axis. An assembly having two suchconnecting members may be secured in a reliable manner to the pipeparts. Each of the further first fastening member and the further secondfastening member may then comprise a primary bolt member adapted to besecured in a primary recess in the first pipe part and the second pipepart, respectively.

According to a further embodiment of the invention, the assembly isadapted to secure and maintain a tubular T-connection assembly in anuclear reactor, the tubular T-connection assembly being formed by amain pipe extending along a longitudinal axis and having cylindricalwall and a closed end, the first pipe part and the second pipe part, thefirst pipe part being connected to the main pipe via the cylindricalwall at a first interface, the second pipe part being connected to themain pipe via the cylindrical wall at a second interface and the firstand second pipe parts extending outwardly from the cylindrical wall in aopposite directions along the primary axis. Advantageously, the platesmay be adapted to be provided outside the closed end of the main pipe.

According to a further embodiment of the invention, the primary axis isperpendicular or substantially perpendicular to the longitudinal axis.

According to a further embodiment of the invention, the primary axis isperpendicular or substantially perpendicular to the secondary axis.

According to a further embodiment of the invention, an intermediate pipepart is arranged between the first pipe part and the second pipe part.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely through thedescription of various embodiments and with reference to the drawingsattached hereto.

FIG. 1 discloses schematically a partly cut perspective view of aboiling water nuclear reactor.

FIG. 2 discloses a perspective view of a core spray supply system forthe reactor in FIG. 1.

FIG. 3 discloses a perspective view of a mechanical securing assemblyaccording to a first embodiment of the invention at a T-box assembly.

FIG. 4 discloses a perspective view the mechanical securing assembly inFIG. 3.

FIG. 5 discloses another perspective view the mechanical securingassembly in FIG. 3.

FIG. 6 discloses a sectional view through the mechanical securingassembly in FIG. 3.

FIG. 7 discloses a perspective view of a mechanical securing assemblyaccording to a second embodiment of the invention.

FIG. 8 discloses a perspective view of the mechanical securing assemblyin FIG. 7 mounted to two pipe parts.

FIG. 9 discloses a perspective view of a mechanical securing assemblyaccording to a third embodiment of the invention.

FIG. 10 discloses a perspective view of the mechanical securing assemblyin FIG. 9 mounted to two pipe parts.

FIG. 11 discloses a perspective view of a mechanical securing assemblyaccording to a fourth embodiment of the invention.

FIG. 12 discloses an exploded view of the mechanical securing assemblyin FIG. 11.

FIG. 13 discloses a perspective view of a mechanical securing assemblyaccording to a fifth embodiment of the invention.

FIG. 14 discloses a perspective view of the mechanical securing assemblyin FIG. 13 mounted to two pipe parts.

FIG. 15 discloses a perspective view of a mechanical securing assemblyaccording to a sixth embodiment of the invention.

FIG. 16 discloses a perspective view of the mechanical securing assemblyin FIG. 15 mounted to two pipe parts.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

FIG. 1 shows schematically a boiling water nuclear reactor 1, whichcomprises a reactor pressure vessel 2 with a wall 3. The reactorpressure vessel 2 encloses a core 4 of fuel assemblies 5 only a few ofwhich are indicated. The fuel assemblies 5 are supported at the bottomby core plate 6 and at the top by a top guide 7. A core shroud 8, seealso FIG. 2, surrounds the core 4 and is arranged within the reactorpressure vessel 2. The nuclear reactor 1 also comprises a number ofpumps, in the embodiment disclosed in the form of jet pump assemblies 9,for transferring cooling water into the reactor pressure vessel 2 forcooling of the core A.

The nuclear reactor 1 also comprises a core spray system for sprayingcooling water on the core 4 in case of overheating. The core spraysystem comprises an upper tubular core spray sparger 21 and a lowertubular core spray sparger 22, see FIG. 2, both of which havesemi-circular configuration. The core spray spargers 21, 22 are orientedhorizontally within a upper cylindrical section of the shroud 8 abovethe top guide 7. The core spray spargers 21, 22 comprises a plurality ofsparger nozzles 23, see FIG. 3, for supplying water to the core 4. Thesemi-circular core spray spargers 21, 22 are arranged in opposed pairsto form circular rings at an upper level and a lower level. The corespray spargers 21, 22 are connected to inlet members formed in thereactor pressure vessel 2 above the shroud 8 via core spray supplypiping.

The inlet members comprises a flow divider or T-box assembly 24 disposedin the reactor pressure vessel 2 above the shroud 8. The core spraysupply piping includes a pair of horizontal pipes 25, which extendcircumferentially in opposite directions from a T-box assembly 24 to apair of upper elbows 26 where the piping turns downwardly to connectwith a pair of vertical pipes 27. Each vertical pipes 27 extenddownwardly from one of the upper elbows 26 to a lower elbow 28 where thepiping turns inwardly to penetrate trough the shroud 8 and connect tothe upper core spray sparger 21 and the lower core spray sparger 22.Each lower elbow is connected to the respective core spray sparger 21,22 via a T-box assembly 31, 32, see FIG. 3. Each T-box assembly 31, 32,see FIGS. 3, 6 and 11, is formed by a main pipe 33 extending along alongitudinal axis x and having cylindrical wall 34 and a closed end 35.A first pipe part 41 of the core spray sparger 21, 22 is connected tothe main pipe 33 via the cylindrical wall 34 at a first interface. Asecond pipe part 42 the core spray sparger 21, 22 is connected to themain pipe 33 via the cylindrical wall 34 at a second interface. Thefirst and second pipe parts 41, 42 extend outwardly from the cylindricalwall 34 in opposite directions along a primary axis y.

FIGS. 3-6 disclose a first embodiment of a mechanical securing assembly40 adapted to secure the structural integrity of a flow passage formedby the first pipe part 41 and the second pipe part 42. In the embodimentdisclosed in FIGS. 3-6, the mechanical securing assembly is provided onthe lower T-box assembly 32, wherein the first pipe part 41 and thesecond pipe part 42 are formed by portions of the lower core spraysparger 22. It is to be noted, however, that the mechanical securingassembly 40 of the first embodiment may be used to secure the integrityof any pipes in the nuclear plant.

The mechanical securing assembly comprises a connecting member 43, afirst fastening member 44 and a second fastening member 45. The firstfastening member 44 is attached to the connecting member 43 and adaptedto secure the connecting member 43 to the first pipe part 41. The secondfastening member 45 is attached to the connecting member 43 and adaptedto secure the connecting member 43 to the second pipe part 42. Theconnecting member 43 comprises a spring element 46 exerting a forcepulling the first fastening member 44 and the second fastening member 45towards each other along or in parallel with the primary axis y.Consequently, the spring element 46 forces the first pipe part 41 andthe second pipe part 42 towards each other and against the main pipe 33of the T-box assembly 30.

Each of the first fastening member 44 and the second fastening member 45comprises a primary bolt member 51 adapted to be secured in a primaryrecess 53, see FIG. 6, in the first pipe part 41 and the second pipepart 42, respectively. Furthermore, in the first embodiment, each of thefirst fastening member 44 and the second fastening member 45 comprises asecondary bolt member 52 adapted to be secured in a secondary recess inthe first pipe part 41 and the second pipe part 42, respectively. Theconnecting member 43 is thus attached to the pipe parts 41, 42 by meansof four bolt members, wherein each of the primary bolt members 51extends along a primary direction into the primary recess 53 and each ofthe secondary bolts member 52 extends along a secondary direction intothe secondary recess. As can be seen in FIG. 3, the primary directionforms an acute angle with the secondary direction. The four bolt memberswill thus form means adapted to secure the connecting member 43 to thepipe parts 41, 42 with respect to the primary axis y and thelongitudinal axis x.

The spring element 46 is extendable along the primary axis y by acompression of the spring element 46 along a secondary axis z forming anangle to the primary axis y, in the embodiment disclosed an angle ofabout 90°. The spring element has a flat or substantially flat andannular shape. Such an annular shape may be circular or substantiallycircular, oval, elliptic or the like. Also a polygonal basic shape ispossible, although the corners of such polygon advantageously arerounded. Furthermore, the connecting member 43 has a first portion 54,extending between the first fastening member 44 and the spring element46, and a second portion 55 extending between the second fasteningmember 45 and the spring element 46. The first portion 54 and the secondportion 55 may extend in opposite directions from the spring element,e.g. in parallel with the primary axis y. The spring element 46 is madeof sheet metal. Furthermore, all parts of the connecting member 43, i.e.the spring element 46, the first portion 54 and the second portion 55,may thus form an integrated part made of one single piece of sheetmaterial, wherein the connecting member 46 may have a flat or planeshape.

FIGS. 7 and 8 disclose a second embodiment, which differs from the firstembodiment in that the primary direction of the primary bolt members 51is substantially opposite to the secondary direction of the secondarybolt members 52. It is to be noted that the same reference signs havebeen used in all embodiments for designating elements having the same orsubstantially the same function. The primary and secondary bolt members51 and 52 in the second embodiment will thus be introduced into therespective recesses 53 from a respective side of the pipe parts 41 and42. This embodiment is suitable for all kinds of pipes, especially whenthere is enough space to permit the fastening members 44, 45 to beattached at two opposite sides of a pipe.

FIGS. 9 and 10 disclose a third embodiment, which differs from theprevious embodiments in that the mechanical securing assembly 40comprises also a further connecting member 43′, a further firstfastening member 44′, attached to the further connecting member 43′ andadapted to secure the further connecting member 43′ to the first pipepart 41, and a further second fastening member 45′ attached to thefurther connecting member 43′ and adapted to secure the furtherconnecting member 43′ to the second pipe part 42. The further connectingmember 43′ comprises a further spring element 46′ exerting a forcepulling the further first fastening member 44′ and the further secondfastening member 45′ towards each other along or in parallel with theprimary axis y.

Consequently, also the further spring element 46′ is adapted to forcethe first pipe part 31 and the second pipe part 42 towards each other.Also the further spring element 46′ is extendable in parallel with theprimary axis y by a compression of the further spring element 46′ inparallel with the secondary axis z forming an angle to the primary axis,especially an angle of 90°. Each of the further first fastening member44′ and the further second fastening member 45′ comprises a primary boltmember 51 adapted to be secured in a primary recess in the first pipepart and the second pipe part, respectively. The primary bolt member 51of the fastening members 44 and 45 extends in a direction opposite tothe direction of the primary bolt member 51 of the further fasteningmembers 44′ and 45′.

In the third embodiment, the connecting member 43 and the furtherconnecting member 43′ are thus identical or substantially identical butturned in opposite directions so that the primary bolt members 51 aredirected towards each other. The connecting member 43 and the furtherconnecting member 43′ are connected to each other by means of an element56 which in the third embodiment is shaped as a rod.

FIGS. 11 and 12 disclose a fourth embodiment which comprises only oneconnecting member 43 and a clamping member 60 adapted to secure theconnecting member 43 to the pipe parts 41. 42 with respect to thelongitudinal direction x that is perpendicular to the primary axis y.The clamping member 60 encloses, in the fourth embodiment, a part of anouter periphery of the second pipe part 42.

The clamping member 60 comprises a first plate 61, provided outside thespring element 46 of the connecting member 43, and a second plate 62provided outside the first plate 61. The first plate 61 has a circularopening 63. The second plate 62 has a circular protrusion 64 which isintroduced into and fitted in the circular opening 63 of the first plate61. The second plate 62 is thus rotatable with respect to the firstplate 61 around a common center axis when the plates 61, 62 are arrangedbeside each other and against the connecting member 43.

The first plate 61 carries a first clamp element 71. The second plate 62carries a second clamp element 72 adapted to co-operate with the firstclamp element 61 in order to clamp the second pipe part 42 therebetweenby rotating the first and second plates 61 and 62 relatively to eachother and to the connecting member 43. The second plate 62 also carriesa third clamp element 73 adapted to engage the first pipe part 41 as aresult of the rotation of the plates 61 and 62. The rotation of theplates 61 and 62 relatively each other is accomplished by means of amounting toll (not disclosed). The clamping member 60 is then locked inthe clamping position by means of a screw bolt 74 provided in a threadedhole through the third clamp element 73.

The mechanical securing assembly 40 according to the fourth embodimentis particularly adapted to secure and maintain the T-box assembly 31 ofupper sparger 21, the T-box assembly 32 of the lower sparger 22 as shownin FIG. 8, or the T-box assembly 24 of the core spray supply piping. Theplates 61, 62 are then provided outside the closed end 35 of the mainpipe 33 of the respective T-box assembly 24, 31, 32.

FIGS. 13 and 14 disclose a fifth embodiment, which differs from theprevious embodiments in that mechanical securing assembly 40 is adaptedto secure a first pipe part 41 extending along a first direction and asecond pipe part 42 extending along a second direction to anintermediate angled pipe part 49, wherein the first and seconddirections are perpendicular to each other. The first fastening member44 with the primary bolt member 51 secures the connecting member 43 tothe first pipe part 41 and the second fastening member 45 with theprimary bolt member 51 secures the connecting member 43 to the secondpipe part 42. The spring element 46 exerts a force pulling the firstfastening member 44 and the second fastening member 45 towards eachother along a primary axis y. Consequently, the connecting member 43 andthe spring element 46 force the first pipe part 41 and the second pipepart 42 against the intermediate angled pipe part 49 and thus towardseach other.

FIGS. 15 and 16 disclose a sixth embodiment, which differs from thefifth embodiment in that mechanical securing assembly 40 comprises athird fastening member 83 having a primary bolt member 51 and adapted tosecure the connecting member tot the intermediate angled pipe part 49.The first fastening member 44 with the primary bolt member 51 securesthe connecting member 43 to the first pipe part 41 and the secondfastening member 45 with the primary bolt member 51 secures theconnecting member 43 to the second pipe part 42. The spring element 46exerts a force pulling the first fastening member 44 and the secondfastening member 45 towards each other along the primary axis y, whereinthe third fastening member 83 acts as a support on the intermediate pipemember 49. Consequently, the connecting member 43 and the spring element46 will also in this embodiment force the first pipe part 41 and thesecond pipe part 42 against the intermediate angled pipe part 49 andthus towards each other. The spring element 46 is extendable along theprimary axis y by compressing the spring element 46 along a secondaryaxis z′ and/or z″ forming an angle to the primary axis y.

It is to be noted that the first fastening members 44, and the secondfastening members 45, as an alternative solution within the scope of theclaimed invention, may comprise other means than the bolts 51, 52disclosed above. For instance, each fastening member 44, 45 may compriseany suitable kind of clamping member, adapted to engage or grip, bymeans of friction, at least a part of the outer periphery of therespective pipe part 41, 42.

The intermediate pipe part 83 may have another angle than the rightangle disclosed in FIGS. 14 and 16. The intermediate pipe part 49 mayalso have a straight extension in parallel with the primary axis y.

The present invention is not limited to the embodiments disclosed butmay be varied and modified within the scope of the following claims.

1. A mechanical securing assembly adapted to secure the structuralintegrity of a flow passage formed by at least a first pipe part and asecond pipe part, the assembly comprising: a connecting member; a firstfastening member attached to the connecting member and adapted to securethe connecting member to the first pipe part; and a second fasteningmember attached to the connecting member and adapted to secure theconnecting member to the second pipe part, wherein the connecting membercomprises a spring element exerting a force pulling the first fasteningmember and the second fastening member towards each other along aprimary axis (y), and thus being adapted to force the first pipe partand the second pipe part towards each other, wherein the spring elementis extendable along the primary axis (y) by a compression of the springelement along a secondary axis (z) forming an angle to the primary axis(y).
 2. An assembly according to claim 1, wherein the spring element hasan annular shape.
 3. An assembly according to claim 1, wherein theconnecting member has a first portion extending between the firstfastening member and the spring element, and a second portion extendingbetween the second fastening member and the spring element.
 4. Anassembly according to claim 3, wherein the first portion and the secondportion extend in opposite directions from the spring element.
 5. Anassembly according to claim 1, wherein the spring element is made ofsheet metal.
 6. An assembly according to claim 1, wherein each of thefirst fastening member and the second fastening member comprises aprimary bolt member adapted to be secured in a primary recess in thefirst pipe part and the second pipe part, respectively.
 7. An assemblyaccording to claim 1, wherein the assembly comprises means adapted tosecure the connecting member to the pipe parts with respect to adirection (x) being perpendicular to the primary axis (y).
 8. Anassembly according to claim 6, wherein the assembly comprises meansadapted to secure the connecting member to the pipe parts with respectto a direction (x) being perpendicular to the primary axis (y), andwherein said means comprises, in each of the first fastening member andthe second fastening member, a secondary bolt member adapted to besecured in a secondary recess in the first pipe part and the second pipepart, respectively.
 9. An assembly according to claim 8, wherein each ofthe primary bolt members extends along a primary direction into theprimary recess and each of the secondary bolts member extends along asecondary direction into the secondary recess, wherein the primarydirection forms an angle with the secondary direction.
 10. An assemblyaccording to claim 8, wherein each of the primary bolt members extendsalong a primary direction into the primary recess and each of thesecondary bolt members extends along a secondary direction into thesecondary recess, wherein the primary direction is substantiallyopposite to the secondary direction.
 11. An assembly according to claim7, wherein said means comprises a clamping member adapted to secure theconnecting member to the pipe parts with respect to a direction (x)being perpendicular to the primary axis (y) by enclosing at least a partof an outer periphery of at least one of the first pipe part and thesecond pipe part.
 12. An assembly according to claim 11, wherein theclamping member comprises a first plate provided outside the springelement and comprising a first clamp element, and a second plateprovided outside the first plate and comprising a second clamp element,wherein the plates are rotatable relatively to each other to displacethe clamp elements towards and away from each other.
 13. An assemblyaccording to claim 1, wherein the assembly comprises: a furtherconnecting member; a further first fastening member attached to thefurther connecting member and adapted to secure the further connectingmember to the first pipe part; and a further second fastening memberattached to the further connecting member and adapted to secure thefurther connecting member to the second pipe part, wherein the furtherconnecting member comprises a further spring element exerting a forcepulling the further first fastening member and the further secondfastening member towards each other in parallel with the primary axis(y), and thus being adapted to force the first pipe part and the secondpipe part towards each other, and wherein the further spring element isextendable in parallel with the primary axis (y) by a compression of thefurther spring element along a secondary axis forming an angle to theprimary axis (y).
 14. An assembly according to claim 13, wherein each ofthe further first fastening member and the further second fasteningmember comprises a primary bolt member adapted to be secured in aprimary recess in the first pipe part and the second pipe part,respectively.
 15. An assembly according to claim 12, wherein theassembly is adapted to secure and maintain a T-box assembly in a nuclearreactor, the T-box assembly being formed by a main pipe extending alonga longitudinal axis (x) and having a cylindrical wall and a closed end,the first pipe part and the second pipe part, the first pipe part beingconnected to the main pipe via the cylindrical wall at a firstinterface, the second pipe part being connected to the main pipe via thecylindrical wall at a second interface and the first and second pipeparts extending outwardly from the cylindrical wall in a oppositedirections in parallel with the primary axis (y).
 16. An assemblyaccording to claim 15, wherein the plates are adapted to be providedoutside the closed end of the main pipe.
 17. An assembly according toclaim 13, wherein the primary axis (y) is perpendicular or substantiallyperpendicular to the longitudinal axis (x).
 18. An assembly according toclaim 1, wherein the primary axis (x) is perpendicular or substantiallyperpendicular to the secondary axis (z).
 19. An assembly according toclaim 1, wherein an intermediate pipe part is arranged between the firstpipe part and the second pipe part.